A semiconductor manufacturing process includes plasma processing in which etching, film formation, or the like is performed by a plasma of a reactant gas. As for an apparatus for performing such plasma processing, there is known a plasma processing apparatus disclosed in Japanese Patent Application Publication No. 2006-324023. In this plasma processing apparatus, a plasma is generated by exciting a processing gas at an upper portion in a processing chamber and radicals that have passed through an ion trap unit are supplied to a substrate.
When the processing gas is excited in the processing chamber during the plasma processing, there may be employed, e.g., a method for supplying a high frequency power to an antenna, generating an induced electric field in the processing chamber, exciting the processing gas supplied into the processing chamber, and supplying the excited processing gas to a semiconductor wafer (hereinafter, referred to as “wafer”). Since, however, the induced electric field for exciting the processing gas in a space is not uniform, plasma distribution tends to be non-uniform. Further, plasma distribution is easily affected by a magnetic field or an electric field and it is difficult to control a density thereof. Therefore, it is difficult to obtain uniform in-plane distribution of radicals supplied to the wafer. Recently, along with miniaturization of a circuit pattern formed on a wafer, a higher accuracy is required for the in-plane uniformity of the wafer processing. Accordingly, there is required a technique for controlling in-plane distribution of the processing on the substrate in a processing module.
Japanese Patent No. 5192214 discloses a technique for adjusting concentration of a gas by supplying an additional gas to a peripheral portion of a wafer W and adjusting in-plane uniformity of the wafer W. However, it is disadvantageous in that the additional gas is difficult to be supplied to a central portion of the wafer W. In addition, an example in which a processing gas is turned into a plasma and the plasma thus generated is supplied to the wafer is not considered.